Uploaded April 2024 | Updated September 2026, 2 weeks ago
A smoke bomb produces a thick cloud of billowing smoke that disperses in about a minute. Such bombs have obvious military and law enforcement applications but can also be used to add visual impact to celebrations, ceremonies, videos and photographs. They are also sometimes used by demonstrators to stir up passions. The effect is more dramatic when the smoke is coloured. How do they work?
Let’s start the story with gummy bears. A classic chemical demonstration involves heating a bit of potassium chlorate in a test tube until it melts and then dropping in a gummy bear, which is essentially sugar. Heating potassium chlorate causes it to decompose into potassium chloride and oxygen. The heat also ignites the sugar which then begins to burn ferociously thanks to the copious amounts of oxygen now present. Flames and smoke shoot out of the test tube.
Smoke is essentially made of fine particles that are opaque to light and are suspended in air. In the case of the burning gummy bear, those particles are potassium chloride and unburned bits of gummy bear. A smoke bomb features the same chemistry, but instead of a gummy bear, pure sugar is used. A cardboard tube is packed with a mixture of sugar and potassium chlorate and is fitted with a pull-wire igniter. This is a simple device that creates friction and a spark as the wire is pulled, very much like striking a match against the side of a matchbox. The wire has a bit of black powder on it that catches fire and ignites the sugar-potassium chlorate mixture. Sodium bicarbonate in the mix absorbs some of the heat and prevents the reaction from becoming too vigorous.
To produce coloured smoke, powdered organic dyes, the same ones used to colour fabrics, such as indigo or various anthraquinones, are added to the mix. The heat of combustion turns these into a vapour, and when that vapour hits the cooler air it condenses into tiny coloured particles. Combustion of the sugar yields a large amount of carbon dioxide and water vapour that help disperse the dye particles. It is all very impressive but obviously inhaling the smoke is not a good thing. And it should be remembered that when you ignite a smoke bomb, you are igniting a mini rocket engine and you are playing with fire. You can get burned.
A smoke bomb produces a thick cloud of billowing smoke that disperses in about a minute. Such bombs have obvious military and law enforcement applications but can also be used to add visual impact to celebrations, ceremonies, videos and photographs. They are also sometimes used by demonstrators to stir up passions. The effect is more dramatic when the smoke is coloured. How do they work?
Let’s start the story with gummy bears. A classic chemical demonstration involves heating a bit of potassium chlorate in a test tube until it melts and then dropping in a gummy bear, which is essentially sugar. Heating potassium chlorate causes it to decompose into potassium chloride and oxygen. The heat also ignites the sugar which then begins to burn ferociously thanks to the copious amounts of oxygen now present. Flames and smoke shoot out of the test tube.
Smoke is essentially made of fine particles that are opaque to light and are suspended in air. In the case of the burning gummy bear, those particles are potassium chloride and unburned bits of gummy bear. A smoke bomb features the same chemistry, but instead of a gummy bear, pure sugar is used. A cardboard tube is packed with a mixture of sugar and potassium chlorate and is fitted with a pull-wire igniter. This is a simple device that creates friction and a spark as the wire is pulled, very much like striking a match against the side of a matchbox. The wire has a bit of black powder on it that catches fire and ignites the sugar-potassium chlorate mixture. Sodium bicarbonate in the mix absorbs some of the heat and prevents the reaction from becoming too vigorous.
To produce coloured smoke, powdered organic dyes, the same ones used to colour fabrics, such as indigo or various anthraquinones, are added to the mix. The heat of combustion turns these into a vapour, and when that vapour hits the cooler air it condenses into tiny coloured particles. Combustion of the sugar yields a large amount of carbon dioxide and water vapour that help disperse the dye particles. It is all very impressive but obviously inhaling the smoke is not a good thing. And it should be remembered that when you ignite a smoke bomb, you are igniting a mini rocket engine and you are playing with fire. You can get burned.
